I can't go through this part of the game in the Death God's Vault, when you must traverse a corridor of enemies among which one is a Lich King. He will just cast some bullshit spell on my main character that will leave him dazed FOREVER. And I mean it. Sometimes it's well over 20 (twenty) rounds. Sometimes the bastard will cast on the other companions too and, whatever the case, they become dazed until they are all killed. How many turns does this 'Lich King's Daze' last? How can I prepare against this?

I don't remember the stats of the lich king BUT I remember this battle is optional at the beginning of the expansion. Eventually, almost at the end, you are truly forced to defeat them BUT you would be closer to lvl 30 than before with extra saves and epic spells.

If you are already on that situation... Mind blank spell could be useful (again I can't remember the details). It's a very tricky fight (worse than a legion of epic vampires) as you need to understand very well the spell mechanics and defenses against them.